So each time a post "just asking questions" is posted, close it with a link to the explanation of why the idea has already been debunked. Just like a Bugzilla dupe or a StackOverflow dupe.
For a long time, Reddit moderators did not have the tools to do this. Regardless, whenever bad-faith argumentation is removed, the person whose comment was removed paints the event as censorship which just backs up their conspiracy argument more
Spam detection has been a feature of email clients for a long time. I'm sure even a rudimentary automated detection mechanism could prevent a significant portion of the dupes.
In order to have a good community, you need a form of censorship, whether through moderation, spam detection, voting systems, and so on. Otherwise, the community as a whole becomes a mess.
